(1) Field of the Invention
The present invention relates to novel compounds that are isolatable from cherries and have antioxidant activity and methods for isolating these compounds. In particular, the invention relates to 1-(3',4'-dihydroxycinnamoyl)-cyclopenta-2,3-diol and 1-(3',4'-dihydroxycinnamoyl)-cyclopenta-2,5-diol, which have antioxidant activity. These antioxidant compounds and compositions containing these compounds are useful as food preservatives, dietary supplements, nutraceuticals, and phytoceuticals.
(2) Description of Related Art
Many plant-derived compounds impart important positive or nutriceutical/phytoceutical traits to foods by way of their abilities to serve as cellular antioxidants by maintaining low levels of reactive oxygen intermediates, as anti-inflammatory agents by inhibiting prostaglandin synthesis, or as inhibitors of enzymes involved in cell proliferation. These activities may be important in ameliorating chronic diseases such as cancer, arthritis, and cardiovascular disease, which in some cases may be caused in part by free radicals (Kinsella et al. (1993). Food Technol. 47: 85-9).
Free radicals have been implicated in a number of pathological processes, which include aging, inflammation, reoxygenation of ischemic tissues, atherosclerosis, and various kinds of cancer (Halliwell et al. (1990). Methods Enzymol. 186: 1-88). The harmful activities of free radicals such as hydroxyl (OH.sup.-) and peroxyl (ROO.sup.-) radicals, and the superoxide anion (O.sup.-.sub.2) are constantly being produced as a result of metabolic reactions in living systems (Halliwell et al. ibid.). Living systems are protected from oxidative damage by these reactive species by enzymes such as superoxide dimutase and glutathione peroxidase, and by antioxidant compounds such as ascorbic acid, tocopherols, and carotenoids (Sies (1997). Exp. Physiol. 82: 291-5). However, when free radical production exceeds the antioxidant capacity of the organism, these free radicals attack lipids, proteins and DNA, thus damaging structural integrity and function of cell membranes, enzymes, and genetic material (Byers et al. (1992). Ann. Rev. Nutr. 12: 139-59). A growing body of evidence indicates that various pathological conditions such as cardiovascular disease, arthritis, various cancers, and Alzheimer's disease are associated, at least in part, with the damaging effects of uncontrolled free radical production (Byer et al. ibid.). It is also well known that lipids in meats are prone to oxidation, which contributes to rancidity in cooked and uncooked foods and natural lipid products for a variety of uses. It is also well known that cooking meats causes the formation of hetrocyclic aromatic amines (HAA) and other oxidative products. HAAs are dietary compounds that are formed naturally during cooking of muscle foods and are thought to arise from reactions involving creatine or creatinine, sugars, and amino acids. It has been shown that these HAAs are carcinogenic. Thus, compounds which would inhibit formation of HAAs during the cooking process would be particularly useful.
Many foods contain non-nutritive components such as flavanoids and other phenolic compounds which may provide protection against chronic disease through a multiplicity of effects which are still poorly understood (Tanaka et al. (1993). Carcinogenesis 14: 1321-5). These compounds may act as antioxidants by reacting with free radicals and thus interrupting the propagation of new free radical species, or by chelating metal ions such as Fe.sub.2+ which catalyze lipid oxidation to alter their redox potentials. Therefore, naturally occurring antioxidants can be useful for treating various diseases. Thus, there is a need to identify antioxidative compounds from natural products. Since antioxidants may have ancillary effects, there is a need for novel antioxidant compounds which have beneficial effects not available with known antioxidants.
These natural antioxidant compounds could provide the food industry with natural compounds which would not only enhance food stability, but could also provide significant health benefits to the consumer. For example, antioxidants added to lipid containing products would extend the shelf life of these products. Antioxidant compounds would also be useful for the treatment of chronic diseases, either in prevention of disease, ameliorating the effects of disease, or stimulating the immune response to more effectively combat disease. There is evidence that has shown that some antioxidant supplements can significantly improve certain immune responses (Hertog et al. (1993). Lancet 342: 1007-11).
Finally, as the general population becomes older, the public interest in phytoceuticals as a means to inhibit chronic diseases and aging has steadily increased. The present invention addresses these interests by providing novel antioxidants which are effective at inhibiting oxidation, and can be isolated from natural sources in large quantities, easily and inexpensively.